/*******************************************************************************
 * Copyright (c) 2000, 2015 IBM Corporation and others.
 *
 * This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License 2.0
 * which accompanies this distribution, and is available at
 * https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.jface.viewers;

/**
 * A cell modifier is used to access the data model from a cell
 * editor in an abstract way. It offers methods to:
 * <ul>
 *	<li>to check if a a model element's property can be edited or not</li>
 *	<li>retrieve a value a model element's property</li>
 *	<li>to store a cell editor's value back into the model
 *    element's property</li>
 * </ul>
 * <p>
 * This interface should be implemented by classes that wish to
 * act as cell modifiers.
 * </p>
 */
public interface ICellModifier {
	/**
	 * Checks whether the given property of the given element can be
	 * modified.
	 *
	 * @param element the element
	 * @param property the property
	 * @return <code>true</code> if the property can be modified,
	 *   and <code>false</code> if it is not modifiable
	 */
	public boolean canModify(Object element, String property);

	/**
	 * Returns the value for the given property of the given element.
	 * Returns <code>null</code> if the element does not have the given property.
	 *
	 * @param element the element
	 * @param property the property
	 * @return the property value
	 */
	public Object getValue(Object element, String property);

	/**
	 * Modifies the value for the given property of the given element. Has no effect
	 * if the element does not have the given property, or if the property cannot be
	 * modified.
	 * <p>
	 * Note that it is possible for an SWT Item to be passed instead of the model
	 * element. To handle this case in a safe way, use:
	 * </p>
	 *
	 * <pre>
	 * if (element instanceof Item) {
	 * 	element = ((Item) element).getData();
	 * }
	 * // modify the element's property here
	 * </pre>
	 *
	 * @param element  the model element or SWT Item (see above)
	 * @param property the property
	 * @param value    the new property value
	 *
	 * @see org.eclipse.swt.widgets.Item
	 */
	public void modify(Object element, String property, Object value);
}
